Drive and bearing assemblies for water pumps are not new per se. Typically, these assemblies comprise a housing having a housing flange with an axially outwardly projecting hollow stud to support a roller bearing. The assembly further includes a shaft carrying the pump rotor and pulley that sits on the roller bearing. In accordance with a known prior design shown in West German Registered Design No. 73-39,167, the shaft and the pulley constitute a single part as illustrated in FIG. 2 of this design.
In the design described above, the bearing comprises a single roller bearing having a set of rollers and a set of balls. This bearing centers the pulley and by means of a coupling element centers the shaft which carries the pump rotor without the need for a second bearing. However, since this bearing is not tightened axially, the pulley is not guided with precision in the axial direction and thus the shaft also lacks axial guidance. This results in increased noise levels. Furthermore by reason of imprecise axial guidance, there is a danger that the belt running on the pulley, particularly a flat belt will wobble and flutter and additionally the slip ring seal normally used tends to wear rapidly.